The overall objectives of the proposed research are to acquire basic information on infections with Wuchereria bancrofti and Brugia spp., lymphatic-dwelling filarial parasites on man and animals. Recent success in establishing the periodic strain of W. bancrofti in macaque monkeys now provides further opportunities for the study of this important human parasite. During the next project period it is planned to expand our efforts at establishing monkey-to-monkey transmission of the parasite so that a laboratory source for infecting mosquitoes is continually available. Successful transmission will allow for further characterization of developing and patent infections in monkeys as well as providing the opportunity for further studies on the transmission of W. bancrofti to rodent hosts. Work will continue on the Brugia-jird model with emphasis being placed on B. pahangi infections. Immunological studies will focus on macrophage-antigen interactions and on circulating immune complexes. The study of the role of macrophages in filarial infections will involve the establishment of markers and lymphocyte subpopulations in jirds, the role of macrophages in cellular cooperation and the immune response to B. pahangi antigen in vitro, the mechanism of macrophage regulation of the immune response to B. pahangi antigen in vitro, and the role of macrophages in the in-vivo immune response to this infection. The role of immune complexes in filariasis will be evaluated by identifying, quantitating, and following over time the complexes detected in infected jird sera. As an adjunct to immunological studies in an inbred strain of jird, inbred strains of rats and mice will be tested for their susceptibility to lymphatic filarial infection.